Can vaporization of biodiesel be increased?

[gdorris]

My understanding of the problem with CR TDIs, such as the 2.0T, is that BD does not vaporize well enough during post injection events, clings to cylinder walls and dilutes crankcase oil, leading to engine wear. I think it may also not burn as hot in the catalyst, but one problem at a time........

Is there an additive that might enhance vaporization of BD to reduce the oil dilution problem? I understand that residual methanol in BD can reduce flash point and increase volatility. Might it not also have a positive effect on vaporization? If not, is there another additive that might?

 

[Lug_Nut]

I suspect petroleum diesel additive to 95% might be enough to keep the system functioning.

Almost makes me wish that the AdBlue was an option for the smaller cars....
(that comment is based on my understanding that the NOx treatment/conversion used on the larger cars does not also use the supplemental squirt from the cylinder injectors to fuel the after-burn).

 

[UFO]

I suspect petroleum diesel additive to 95% might be enough to keep the system functioning.

With plenty of margin, I'm sure.

 

[gdorris]

My understanding of the problem with CR TDIs, such as the 2.0T, is that BD does not vaporize well enough during post injection events, clings to cylinder walls and dilutes crankcase oil, leading to engine wear. I think it may also not burn as hot in the catalyst, but one problem at a time........

Is there an additive that might enhance vaporization of BD to reduce the oil dilution problem? I understand that residual methanol in BD can reduce flash point and increase volatility. Might it not also have a positive effect on vaporization? If not, is there another additive that might?

Seriously now, anyone with a chemistry background know if it is possible?

 

[BKmetz]

The only way to improve an oil's vaporization/atomization characteristics is to change its viscosity, either by heating it and/or thinning it. Simple physics.

 

[BioDiesel]

"is that BD does not vaporize well enough "

I think you've misunderstood the problem.

BD vaporizes just fine in a TDI, even a 2009.
The real problem is that fuel injection timing is delayed to force the fuel to burn while exiting the chamber, thus raising the exhaust system temerature.

Incompletely burned fuel results. Not a big problem for petro diesel, it evaporates usually. [IIRC One petro user reported something like 1liter cc accumulation / 1000 km! ]

Heating would drop the viscosity and maybe reduce the amount of incompletely burned fuel. But probably not enough to see a big difference.
iirc, th evisc. vs temp. curve for bd is more or less flat.
Not like vo's which is exponential.


If you want to run bd, you might try a plant-based ecc oil that is reported to be tolerant of vo and bd . FUCHS-DEA Planto-Mot

 

[validius]

The simple answer is that you cannot have your cake and eat it too. The EPA has determined that soot&NOX emissions are the most important thing to take care of. If you want your Bio then get and older car and chill out till we have found an effective way of removing the emissions devices from the 09's.

Please don't try to play with fire on this. If you have to ask questions like this you are not qualified to do any R&D on this.

 

[nesdon]

soot?

Validius, I have concrete empirical evidence that B100 significantly reduces soot formation. Therefore re: that standard, B100 is an advantage. Also meaning that other remarks remarks about DPF clogging are spurious.

Reading Bosch's analysis, the real culprits are contaminants in poor quality fuel and higher oxidation rates. I always use Sta-Bil fuel stabilizer in all my garden equiptment, boats and collector cars that have infrequent use, and notice a huge improvement. All the pull start engines start easily after months of sitting. Not at all true for unstabilized fuel.

I suspect this could also help with the problems with B100

 

[BKmetz]

Validius, I have concrete empirical evidence that B100 significantly reduces soot formation. Therefore re: that standard, B100 is an advantage. Also meaning that other remarks remarks about DPF clogging are spurious.

Reading Bosch's analysis, the real culprits are contaminants in poor quality fuel and higher oxidation rates. I always use Sta-Bil fuel stabilizer in all my garden equipment, boats and collector cars that have infrequent use, and notice a huge improvement. All the pull start engines start easily after months of sitting. Not at all true for unstabilized fuel.

I suspect this could also help with the problems with B100

There is also concrete empirical evidence that B100 increases NOX which is a huge part of what the catalyst system is trying to remove per the EPA. The VW TDI CR catalyst system is a three part system, soot removal, NOX removal, and H2S removal. You have to think on these three fronts to understand what is going on and why the system is designed the way it is.

Using Sta-Bil is not going to help any aspect of your fuel, engine, or catalyst system to run better, unless you store your car for months on end. Sta-Bil is a fuel stabilizer that keeps the varnish in suspension, nothing more. There is no magic in a bottle that one can add to the fuel which will cure whatever issues a VW CR TDI engine has running B100. If you believe there is, then the people who sell Diesel Secret request you contact them ASAP.

 

[GoFaster]

It's also worth noting that a mixture of one high-viscosity low-volatility liquid (e.g. biodiesel) with some other low-viscosity high-volatility liquid, will not have the same properties as another liquid that is of uniform composition.

 

[Powder Hound]

There is also concrete empirical evidence that B100 increases NOX and CO2 emissions,

Dang. But can't you count the biologic origin of the carbon and pretend it is carbon-neutral?
[qutoe=BKmetz]... The VW TDI CR catalyst system is a three part system, soot removal, NOX removal, and CO2 removal...[/quote]There has to be a mis-read going on here. Soot gets removed by burning it to CO2. Gotta be something else. And CO2 removal is by pushing the gas out the tailpipe, not by making it into something else, unless you are making some kind of particulate carbide out of CO2 and the NOx.

Oh! Oh! I've got it - you combine the CO2 and NOx and make O2 and... CN. Cyanide!! Yeah, that's the ticket...

 

[BioDiesel]

Nesdon wrote:
"Therefore re: that standard, B100 is an advantage."

Yes you are correct. B100 leads to less soot and DPF plugging. In the Cummins study, their DI diesel ran as clean on B100 w/o a DPF as when LSD fueled WITH a DPF!

The problem is, most buyers will run them on diesel fuel so we're stuck with the DPF.

 

[itchytweed]

I don't think that vaporization of Biodiesel is the issue. The one is of Flash Point and what they have to do to regenerate all of the mileage sapping tailpipe filters.

2D-Diesel F.P. = 125 deg F. 1S-Diesel F.P. = 100 deg F. Neat Biodiesel F.P. = 300 deg F. I believe that VW is relying on this flashpoint issue to allow the filters to heat and regenerate themselves through the manipulation of the combustion process. They can allow B5 because the miniscule amount of Biodiesel does not radically impinge on the flashpoint of the diesel fuel.

I am sure that if all the filters were removed and there was any downstream catalysts that did not need heat regen, Biodiesel would be the way to go.

To lower the flashpoint of Biodiesel would require an analytical chemist / petrochemical engineer and some form of post processing of the ester molecule. My concern here would be that if this was done, would we lose the qualities and benefits (cost and pollution-wise) of burning neat Biodiesel.

 

[validius]

Nesdon wrote:
"Therefore re: that standard, B100 is an advantage."

Yes you are correct. B100 leads to less soot and DPF plugging. In the Cummins study, their DI diesel ran as clean on B100 w/o a DPF as when LSD fueled WITH a DPF!

The problem is, most buyers will run them on diesel fuel so we're stuck with the DPF.

Link to this study or it didnt happen

 

[kcfoxie]

Diesel Secret was mentioned, this thread should be locked!

 

[nicklockard]

I don't think that vaporization of Biodiesel is the issue. The one is of Flash Point and what they have to do to regenerate all of the mileage sapping tailpipe filters.

2D-Diesel F.P. = 125 deg F. 1S-Diesel F.P. = 100 deg F. Neat Biodiesel F.P. = 300 deg F. I believe that VW is relying on this flashpoint issue to allow the filters to heat and regenerate themselves through the manipulation of the combustion process. They can allow B5 because the miniscule amount of Biodiesel does not radically impinge on the flashpoint of the diesel fuel.

I am sure that if all the filters were removed and there was any downstream catalysts that did not need heat regen, Biodiesel would be the way to go.

To lower the flashpoint of Biodiesel would require an analytical chemist / petrochemical engineer and some form of post processing of the ester molecule. My concern here would be that if this was done, would we lose the qualities and benefits (cost and pollution-wise) of burning neat Biodiesel.

Once again, Lug Nut nailed the issue (won the thread) by post #2. The required 'modification' to biodiesel to lower its flash point is dilution with petroleum diesel. Or, you could go all expensive and reduce it to an alkane.

 

[BKmetz]

I re-read my post and I did bungle up some details. The third catalyst in the TDI catalyst system is a H2S trap, not a CO2 trap. As there is little to no sufphur in biodiesel, that is a non-issue. Using biodiesel lowers particulates, unburned HCs, and CO. So by default it has more CO2 coming out the exhaust pipe, as it should. My statement about CO2 is correct, but the context I made it in was all wrong.

Dang. But can't you count the biologic origin of the carbon and pretend it is carbon-neutral?

... The VW TDI CR catalyst system is a three part system, soot removal, NOX removal, and CO2 removal...

There has to be a mis-read going on here. Soot gets removed by burning it to CO2. Gotta be something else. And CO2 removal is by pushing the gas out the tailpipe, not by making it into something else, unless you are making some kind of particulate carbide out of CO2 and the NOx.

Oh! Oh! I've got it - you combine the CO2 and NOx and make O2 and... CN. Cyanide!! Yeah, that's the ticket...

 

[BKmetz]

Diesel Secret was mentioned, this thread should be locked!

LOL...

 

[gdorris]

"is that BD does not vaporize well enough "

I think you've misunderstood the problem.

BD vaporizes just fine in a TDI, even a 2009.
The real problem is that fuel injection timing is delayed to force the fuel to burn while exiting the chamber, thus raising the exhaust system temerature.

Maybe you know better than Dave Hubbard in his popular mechanics article: http://www.popularmechanics.com/automotive/how_to/4311498.html
"The idea is to inject fuel into the exhaust that has been vaporized, and when the fuel comes into contact with the DPF, an exothermic reaction heats it up and incinerates the plug of soot. ... And here is where the pitfall lies for biodiesel users like myself. Most of the manufactures decided to inject fuel into the cylinders just after the cylinder fires and the exhaust valve opens. At this point, the fuel vaporizes and the vapors move down the exhaust to the DPF and clean it. Because biodiesel is denser than conventional diesel fuel (it has a longer hydrocarbon chain) and has a higher distillation temperature and boiling point, it does not vaporize as easily. Some of the fuel ends up adhering to the cylinder wall and runs past the rings, diluting engine oil."

Or, maybe you don't.

Sounds like the flash point of the fuel is not the problem because both diesel and biodiesel burn in the filter, although biodiesel does so at a lower temperature. Vaporization, OTOH, is the problem in that Biodiesel fails to vaporize, sticks to the cylinder walls and slips into the crankcase oil. Thus my original question.

 

[gdorris]

If you want your Bio then get and older car and chill out till we have found an effective way of removing the emissions devices from the 09's.

Please don't try to play with fire on this. If you have to ask questions like this you are not qualified to do any R&D on this.

Please see my reply to Biodiesel above and reassess your own grasp of the issues regarding vaporization of biodiesel in post injection events as the root of the problem with biodiesel in CR TDIs. Feel free to offer an alternate legitimate technical explanation of the problem if you are able. Also please note in my signature I already have plenty of "older cars" for my bio.